1. Field of the Invention
The present invention generally relates to the field of battery connectors, and more particular to a coin battery connector.
2. The Related Arts
Coin batteries that have a disk-shape are often employed in electronic equipments, such as computers, as additional power source or back up power source. Although there are a variety of coin batteries of different sizes available in the market, most of them are very small and are thus sometimes referred to as xe2x80x9cbutton batteriesxe2x80x9d. The coin battery has two major surfaces respectively forming positive and negative electrodes. The positive electrode also extends to a circumferential edge of the disk-shape.
The coin battery is mounted to a circuit board by a xe2x80x9cbattery connectorxe2x80x9d. The battery connector comprises a housing defining a central cavity for receiving the coin battery. Conductive terminals for positive and negative electrodes of the battery are fixed to the housing and electrically connected to the circuit board. A conventional coin battery connector is shown in U.S. Pat. No. 5,980,309 wherein an insulative housing of the connector comprises first and second pairs of side walls delimiting a cavity for receiving the coin battery. Each side wall has a inwardly directed retention flange for securing the battery in the housing. To mount/dismount the battery to/from the housing, two of the side walls are deflected. Inclined surfaces are formed on the side walls for facilitating insertion of the battery into the housing. Since the housing and the side walls are integrally formed with synthetic materials which possess relatively low yielding strength as compared to metals, the side walls may be accidentally broken in mounting/dismounting the battery. Further, the provision of the inclined surface in the retention flanges of the side walls inevitably increases the overall height of the battery connector.
Taiwan Patent Application Nos. 87201003 and 87210779 teach using a metallic member of the positive terminal to form releasable retention means. However, a great force is required to deflect a metal plate of substantial surface area in these conventional designs. In addition, although Taiwan Patent Application No. 87201003 discloses a manual tab for bending the metal plate, the tab is short and small and thus difficult to operate. In addition, inclined surfaces formed on a side wall of the housing are also required in these Taiwan patents, sharing the same problem of size as the previously discussed U.S. patent.
Taiwan Patent Application Nos. 83211243, 83211243A01 and 83211243A02 and Chinese Patent No. 99236125.7 all disclose a battery connector comprising a U-shaped positive terminal. A pair of projections are formed on one limb of the U-shape for retaining a battery in the housing. Since the projections are formed by bending a portion of said limb of the U-shape, a major surface of each projection is substantially parallel to the moving direction of the battery when the battery is inserted into the housing. This makes the projections very resistant to the insertion of the battery. Thus, to mount/dismount the battery to/from the housing, deflecting or bending the limb that is a plate of substantial surface area is required. This causes difficulty in handling the battery, especially when the small size of the battery is taken into account.
In addition, the conventional battery connector has a negative terminal mounted to a bottom of the housing. The negative terminal has a longitudinally extending spring arm projecting in an inclined direction into the housing. The spring arm has an end forming a single contact for engaging the negative electrode of a battery. Some of the conventional battery connectors employ a bifurcate configuration, forming two transversely spaced contacts for more reliably engaging the battery. However, reliability of engagement between the negative terminal and battery can be improved in the longitudinal direction.
It is thus desirable to provide a coin battery connector that alleviates or even overcomes the above disadvantages.
Accordingly, an object of the present invention is to provide a coin battery connector that allows ready insertion of a coin battery therein.
Another object of the present invention is to provide a coin battery connector that allows a coin battery to be inserted into the connector with a low insertion force.
A further object of the present invention is to provide a coin battery connector having longitudinally and transversely offset bifurcate negative terminal for more reliable engagement with a negative electrode of a battery.
A further object of the present invention is to provide a coin battery connector comprising a positive terminal forming two tabs having a major surface inclined with respect to an insertion direction of a battery for guiding and enhancing insertion of the battery into the connector.
Yet a further object of the present invention is to provide a coin battery connector having a positive terminal forming two retention arms having ends pointing to the battery for preventing the battery from moving out of the connector.
A further object of the present invention is to provide a coin battery connector having a positive terminal comprising a manual operation arm for manually disengaging the positive terminal from the battery.
To achieve the above objects, in accordance with the present invention, a coin battery connector comprises an insluative housing having a flat base and two pairs of walls extending from the flat base, defining a cavity therebetween for receiving a coin battery. Positive and negative terminals are mounted to the housing for respectively engaging positive and negative electrodes of the battery. The positive terminal comprises a base secured to the housing and a contact panel extending from the base for engaging the positive electrode of the battery. Two retention arms extends from the contact panel and have a major surface inclined with respect to an insertion direction of the battery for guiding and facilitating insertion of the battery into the housing. The retention arms have downward directed free ends for engaging and retaining the battery in the housing. A spring tab is formed on the contact panel for biasing the battery against the downward directed ends of the retention arms. The negative terminal has a bifurcate configuration comprising two spaced, longitudinally extending spring arms project upward from a bottom of the housing in an inclined direction into the housing. Each spring arm has a contact for engaging with the negative electrode of the battery. The contacts of the spring arms of the negative terminal are offset with respect to each other in the longitudinal direction and also in a transverse direction to ensure more reliable engagement of the negative terminal with the battery.